These stones respawn on an intermittent basis, so if you don't get the one you want, come back later. There's also a specific location for the Fire Stone.

How long does it take for the fire stone to Respawn?

All 10 of the main stones are available in one spot and they actually respawn after 24 hours just like most of the Strong Spawn overworld Pokémon do—though they won't all appear at the same time.

Is there more than one fire stone in Pokemon sword?

Pokemon Sword & Shield: Every Pokemon That Evolves With The Fire Stone (& Where To Catch Them) Galar doesn't have many Pokemon that can evolve with a Fire Stone roaming around. ... There are only four Pokemon that can use a Fire Stone, and three out of the four of them are from the first generation.